Index: sys/dev/pci/pci_host_generic.c
===================================================================
--- sys/dev/pci/pci_host_generic.c
+++ sys/dev/pci/pci_host_generic.c
@@ -109,6 +109,11 @@
 	struct ofw_bus_iinfo    pci_iinfo;
 };
 
+typedef void (*generic_pcie_quirk)(device_t);
+struct generic_pcie_quirks {
+	generic_pcie_quirk	cb;
+};
+
 /* Forward prototypes */
 
 static int generic_pcie_probe(device_t dev);
@@ -128,6 +133,16 @@
     rman_res_t count, u_int flags);
 static int generic_pcie_release_resource(device_t dev, device_t child,
     int type, int rid, struct resource *res);
+#if defined(__aarch64__)
+static void generic_pcie_quirk_thunderx(device_t);
+#endif
+
+struct generic_pcie_quirks	g_quirks[] = {
+#if defined(__aarch64__)
+	{generic_pcie_quirk_thunderx},
+#endif
+	{NULL}
+};
 
 static int
 generic_pcie_probe(device_t dev)
@@ -144,10 +159,32 @@
 	return (ENXIO);
 }
 
+#if defined(__aarch64__)
+#define	THUNDER_CFG_BASE_TO_ECAM(x)	((((x) >> 36UL) & 0x3) | (((x) >> 45UL) & 1))
+static void
+generic_pcie_quirk_thunderx(device_t dev)
+{
+	struct generic_pcie_softc *sc;
+	rman_res_t start;
+
+	/* Check if we're running on Cavium ThunderX */
+	if (!CPU_MATCH(CPU_IMPL_MASK | CPU_PART_MASK,
+	    CPU_IMPL_CAVIUM, CPU_PART_THUNDER, 0, 0))
+		return;
+
+	sc = device_get_softc(dev);
+	start = bus_get_resource_start(dev, SYS_RES_MEMORY, 0);
+	sc->ecam = THUNDER_CFG_BASE_TO_ECAM(start);
+
+	device_printf(dev, "quirk: ThunderX, setting ECAM to %d\n", sc->ecam);
+}
+#endif
+
 static int
 generic_pcie_attach(device_t dev)
 {
 	struct generic_pcie_softc *sc;
+	struct generic_pcie_quirks *quirk = g_quirks;
 	uint64_t phys_base;
 	uint64_t pci_base;
 	uint64_t size;
@@ -220,6 +257,9 @@
 	ofw_bus_setup_iinfo(ofw_bus_get_node(dev), &sc->pci_iinfo,
 	    sizeof(cell_t));
 
+	/* Run quirks */
+	for (; quirk->cb != NULL; quirk++)
+		(*quirk->cb)(dev);
 
 	device_add_child(dev, "pci", -1);
 	return (bus_generic_attach(dev));
@@ -434,7 +474,8 @@
 		return (0);
 	}
 
-	device_printf(dev, "ERROR: Unknown index.\n");
+	if (bootverbose)
+		device_printf(dev, "ERROR: Unknown index %d.\n", index);
 	return (ENOENT);
 }